"Marriott values our guests and understands the importance of protecting personal information. We have taken measures to investigate and address a data security incident involving the Starwood guest reservation database," the company said in statement on Friday.

"Marriott is working hard to ensure our guests have answers to questions about their personal information with a dedicated website and call center."

Over the weekend, US Senator Chuck Schumer called for Marriott to cover the US $110 (AU$152, UK£80) new passport fee for anyone who's information was compromised.

However, the U.S. State Department announced Monday that guests whose passport number was hacked in the data breach should not apply for a new passport or report their number stolen unless the physical copy of the passport was actually lost or stolen.

Marriott is also offering those who were hacked a year of free personal information monitoring from Kroll -- a risk consulting firm.